The aims of the research proposed here are to study the structure of the insulin receptor and the mechanism by which insulin activates membrane transport systems, in particular the (NA+, K+) ATPase and other Na+ transporters. One aim is to identify functional domains of the insulin receptor involved in monomer-monomer interactions, disulfide bond formation and insulin binding. Another aim is to determine and isolate the components involved in transducing the signal of the insulin receptor interaction to the (Na+, K+) ATPase and other Na+ transporters.